A communication system operates to communicate data between a sending station and a receiving station. The data is communicated upon a communication channel formed between the sending and receiving stations. If necessary, the data to be communicated by the sending station is first converted into a form to permit communication of the data upon the communication channel. The data communicated upon the communication channel is detected at the receiving station. And, subsequent to detection of the data at the receiving station, operations are performed upon the data to recover the informational content thereof.
Many different types of communication systems have been developed and implemented. In some communication systems, the data to be communicated by the sending station to the receiving station is communicated in the electrical form by way of wireline connections interconnecting the sending and receiving stations. And, in some communication systems, the data is communicated in electromagnetic form, by way of radio links formed between sending and receiving stations. And, some communication systems include communication paths between endpoints formed of the sending and receiving stations that include both wireline and radio link portions such that the data is communicated in electrical form along a portion of the communication path and in electromagnetic form along another portion of the communication path.
The communication system is referred to as being a radio communication system when radio links are used to communicate the data in electromagnetic form. In contrast to a conventional wireline communication system that requires electrical connections to be formed between the sending and receiving stations, a radio communication system is inherently mobile. That is to say, because radio links, rather than wireline connections, are used along at least a portion of the communication paths extending between the sending and receiving stations, the sending and receiving stations need not be positioned in fixed locations, connected to wirelines, to permit communications to be effectuated therebetween.
A cellular communication system is a type of radio communication system that has achieved wide levels of usage and has been installed throughout extensive portions of the world. Successive generations of cellular communication systems have been developed. Reference is commonly made to at least three generations of cellular communication systems. A so-called, first-generation, cellular communication system generally refers to a cellular communication system that utilizes an analog modulation technique. An AMPS (advanced mobile phone service) cellular communication system is exemplary of a first-generation, cellular communication system. A so-called, second-generation, cellular communication system typically refers to a cellular communication system that utilizes a digital, multiple-access communication scheme. A GSM (global system for mobile communications) cellular communication system and an IS-95 (interim standard—1995), CDMA (code-division, multiple-access) cellular communication system are each exemplary of a second generation cellular communication system.
Third-generation, cellular communication systems are presently under development. Third-generation, cellular communication systems refer generally to cellular communication systems intended to provide universal communication service, including effectuation of data services, voice services, and multi-media services. Proposals for third-generation, cellular communication systems generally provide for IP (Internet Protocol)-formatted data. And, subsequent-generation, cellular communication systems are also being proposed. Such subsequent-generation cellular communication systems are generally also packet-based communication systems.
In a packet-based, communication system, data that is to be communicated by a sending station to a receiving station is formatted into data packets. And, the data packets are communicated upon the communication channel, usually during discrete bursts, and delivered to a receiving station. The data packets are operated upon by the receiving station to recover the informational content thereof. The communication channel upon which the packet data is communicated typically exhibits fading characteristics such that values of the data contained in a packet, when delivered to the receiving station differs in some values with the corresponding values of the data when transmitted by the sending station.
Operations performed upon the data packets at the receiving station attempt to compensate for the distortion introduced upon the data during its transmission upon the communication channel. If the distortion cannot adequately be compensated for, the informational content thereof cannot be recovered.
Some packet communication systems utilize a packet retransmission scheme in which a data packet is retransmitted by the sending station if the data packet has not been affirmed to have been adequately communicated to the receiving station. ARQ and HARQ retransmission schemes are used in a feedback setup in which the receiving station generates an acknowledgment when the informational content of the data packet is recovered at the receiving station. If the informational content is not acceptably recovered, the acknowledgment is not returned to the sending station. And, in an HARQ system, a negative acknowledgment is also returned to the sending station when the informational content of a data packet cannot acceptably be recovered. Retransmission of the data packet is thereafter effectuated. Multiple retransmissions of the data packet, if necessary, can also be effectuated. By sending multiple transmissions of the data packet, the likelihood that the informational content thereof can be recovered is increased.
1×EV-DO and 1×Ev-DV, cellular system standard specification proposals, related to the proposed cdma2000 system, provide for analogous such retransmission schemes. In such present proposals, packet data is communicated to a mobile station, and a mobile station selectably requests packet retransmission as well as indicating to a base station of such system of channel conditions on a forward link upon which the packet data is communicated. If an initial transmission of a data packet, when received at the mobile station, is in error, the mobile station returns an NAK (negative acknowledgment) to the base station. Additional retransmissions of the data packet occur until the data packet is received correctly or until a maximum number of retransmissions occur. The retransmissions sometimes involve incremental redundancy where subsequent packets contain new parity information, as well as repeat redundancy where the same information is retransmitted.
Such existing retransmission schemes, however, generally perform data combining operations and decoding operations at each successive retransmission of a data packet. This existing operation is computationally-intensive and power-consumptive.
An improved manner by which to communicate packet data pursuant to a retransmission scheme that is less computationally-intensive and power-consumptive would be advantageous.
It is in light of this background information related to packet communication systems that the significant improvements of the present invention have evolved.